Steel vs Aluminum in cold water ?

[Luis H]

Given that your initial gas weight is maybe 6 lbs for an AL80, at the start of a dive do you plan for the rig to be overweighted or the diver?

John

We all agree that the combination of diver plus rig need to be neutral at the end of a dive (I like to be neutral at about 10 ft deep at the end of a dive).

What I don’t like is a very large discrepancy between diver buoyancy and rig buoyancy. This happens with very heavy plates, or weights carried in weight integrated systems, or even lead on back plates.

Some discrepancy in buoyancy is ok IMO. It is just the extremes that I am seeing, that I don’t like (I think is actually dangerous).

I would easily compromise to a denser HP tank since it would drop "overall" out of the water weight. The major reason I won’t get new HP tanks is because that reduces overall weight in my wallet (I have plenty of great steel 72s).

Just relocating weight from my weight belt to my rig, it just seems counter productive, both in and out of the water.

Out of the water I believe in the old “divide and conquer”. It is easier for me to put a separate weight belt on and then a relatively lighter rig, than trying to lift all the weight at once.

I often have to help other divers with weight integrated systems to put it on. Only with double do I ever may need help (I hope) and not always.

To answer your question directly, my rig is going to be a bit over weight.

 

[JohnAC]

Trim is just fine, and yes I have had to remove my rig.

Thanks for your imput, this is very important to me!

Do you have keel weight on you tank when you dive singles.?

 

[spectrum]

Hi all,

I am in the process of switching from a stab jacket bc to a Hog rig. I dive primarily in the Socal area and always wear 7mm suit. I purchased a steel back plate and am wondering about steel vs aluminum tank. I usually dive a barrowed NB aluminum 80, but am considering steel 100.

I have read threads on bouyancy issues with steel tanks in OOA situations, but I am not interested in tech or doubles, just a little more air & less weight on the belt as a rec diver.

Anyone dive 7mm wetsuit, single steel tank, bp/w, Socal area? How much lead are you carrying?

I weigh 186lbs. In my jacket rig I carry 6lbs on AL tank & 22lbs on a belt. I look forward to taking some of that off in the new Hog rig.

Thanks for your comments!

First of all a steel HP-100 is about -1 buoyant empty compared to the neutral aluminum 80 that you are accustomed to. In terms of being able to swim the rig up the 1 pound difference is a non issue.

Even if you were coming from an AL80 it wouldn't matter. Remember that the AL80 is usually 4.4 pounds positive when empty. For that reason the diver carries 4-5 pounds just to neutralize the cylinder buoyancy. When you go steel these cancel out. The cylinder is now non buoyant but you left 4-5 pounds of weight at home too.

In my full cold salt water wetsuit I wear a 20 pound belt and 2 three pound trim weights up in my BC pockets, these 6 pounds are non ditchable like your plate and they let me swim in trim. This is with an E7-80 which is a HP steel cylinder. If I get out of my rig in shallow water I will of course become somewhat buoyant and I need to pay attention to that. For that reason the 20 pounds stays on my belt and none goes into my ditcahble pull-outs Like any other piece of gear it's important to revisit your skills and practice this stuff from time to time.

Just as a reference In the same suit mentioned above I wear a 26 pound weight belt to skin-dive. The -2.5 pound empty buoyancy of my cylinder is all that really sinks me and lets me end the dive without going positive and corking.

Pete

 

[Thalassamania]

Thanks for your imput, this is very important to me!

Do you have keel weight on you tank when you dive singles.?

No, I don't find a need. Pitch trim is easily adjust, as noted earlier, by moving the belt up or down an inch or two and that is a dynamic process, ocurring whenever needed during a dive. Roll trim is maintained by keeping most of the lead toward my ventral surface and there is no need to adjust for yaw.

Why so important?

 

[Luis H]

No, I don't find a need. Pitch trim is easily adjust, as noted earlier, by moving the belt up or down an inch or two and that is a dynamic process, ocurring whenever needed during a dive. Roll trim is maintained by keeping most of the lead toward my ventral surface and there is no need to adjust for yaw.

Why so important?

Yeah...

"Great minds think alike, on the other hand ... so do ours."

I also agree...

 

[JohnAC]

No, I don't find a need. Pitch trim is easily adjust, as noted earlier, by moving the belt up or down an inch or two and that is a dynamic process, ocurring whenever needed during a dive. Roll trim is maintained by keeping most of the lead toward my ventral surface and there is no need to adjust for yaw.

Why so important?

I don't want to buy unnecessary gear, don't want to kill myself & want to have a great time diving. So far, I'm having a blast!

 

[Thalassamania]

Get either a SeaQuest style buckle or a wire buckle with rubber belt, this will make the fore and aft adjustment and tightening much easier, that's all that I find one needs for pitch trim.

 

[Luis H]

I do use a 1 inch easily adjustable crotch strap between the bottom of my backpack to to the front of my weight belt. This controls my rig and my weight belt from moving towards my head. When I need to adjust the weight belt I loosen or tighten the 1 inch fastex buckle in the front of the crotch strap. I can do it wile I am swimming.


By using the buckle to form the loop around the front of the weight belt I can put my weight belt first, then my rig, and last I attach the crotch strap. If I ever wanted to drop my weight belt the crotch strap would never be in the way since it would release on the front with the weight belt.